(1) Field of the invention
This invention concerns a time of flight mass spectrometer and, more specifically, it relates to a time of flight mass spectrometer with an improved resolution.
(2) Description of the Prior Art
When identical energy is applied to ions, flying velocities of the ions are different depending on their mass and, accordingly, a time of flight required for travalling a certain distance is different depending on the mass of the ion. Thus, it is a basic theory of a time of flight mass spectrometer to analyze the mass of an ion depending on the time of flight of the ion.
By the way, since it is actually impossible to apply just the same level of energy to the respective ions, even those ions of a same mass inevitably have a certain spread of energy and, as the result, their time of flight has a certain spread. Then, as this spread becomes greater, the resolution power for the mass analysis is reduced.
Conventional time of flight mass spectrometers are disclosed for instance in U.S. Pat. No. 3,727,047 and Japanese Patent Laid-Open No. 44953/1982. However, these analyzers can not sufficiently overcome the reduction in the resolution power caused by the spread of the energy as described above.